1. Field of Invention
The present invention relates to an antigen peptide which is capable of detecting a wide range of infection by hepatitis C virus (HCV).
2. Related Art
Non-A, non-B hepatitis is an infectious hepatitis which is believed to be transmitted by means of virus as an agent. Although much remains to be known about the transmission route of non-A, non-B hepatitis, transfusion- or blood products-derived non-A, non-B hepatitis represents a serious medical problem as post-transfusion hepatitis.
In 1989 part of the viral gene associated with non-A, non-B hepatitis was cloned and was designated as hepatitis C virus (HCV) (1989, Choo Q. -L. et al., Science 244: 359-362). At about the same time many HCV genes were isolated by many research groups including the applicant of the present invention, leading to the elucidation of structural features thereof.
The deduced HCV gene has a+strand RNA composed of about 9,300 to 9,500 nucleotides as the genome and encodes one stretch of polypeptide having about 3,000 amino acids. The predicted amino acid sequence thereof has a homology with flavivirus or pestivirus and, thereby HCV virus is believed to be an allied virus thereof. From its similarity to the structures of these viruses, it is believed that the polypeptide encoded by the HCV genome, after being synthesized as a single polypeptide in the cell, is cleaved from the amino-terminal into the structural proteins, core, envelope (E1), and NS1 or E2 (NS1/E2), and the non-structural proteins, NS2, NS3, NS4, and NS5, and then each plays its respective role (1991, Houghton, M. et al., Hepatology 14: 381-391).
Conventional methods used to investigate HCV infection involve the use of these polypeptides encoded by the HCV genome to detect antibodies induced within the patient's body. In particular, since antibodies against core, NS3, and NS4 have been found in many patients with HCV, reagents for detecting antigen-antibody reactions have been prepared using as the antigen part of these polypeptides which were produced by means of genetic engineering, and have played a role in identifying the presence of HCV infection.
However, there is no known antigen which is a single polypeptide comprising a combination of epitope peptides alone and which permits a sensitive detection of a wide range of HCV infection.